Why do you insist on building one for music & one for HT.
what i would do is build 2 identical subwoofers, place them in the corners behind the main speakers, and use them for both music and HT. I think that this way you get better quality for both music and HT, at the same price as building two seperate subs!

hi,
forgot about the driver question.
two very popular drivers at a reasonable price are Adire Shiva, and NHT 1259. those are good for music and HT.
wouldn't go with something that's less. you already have the good amps

"Why do you insist on building one for music & one for HT.
what i would do is build 2 identical subwoofers, place them in the corners behind the main speakers, and use them for both music and HT. I think that this way you get better quality for both music and HT, at the same price as building two seperate subs!"

agreed.

The one for HT is for a friend.
The one for music is for me.

Do you think any of the one's I mentioned come close to the Shiva or NHT?

I'm afraid the amps I have are a little underpowered so I was planning to build the best budget subs possible.